mcpherson



o Model. QSheets-Sheet 1. w MQPHERSON -D'OVETAILING MAGHINE- Patented Apr. 24, 1894.

(No Model.) 2 Sheets-Sheet 2.

- W. MOPHERSON.

DOVETAILING MACHINE. I PatentdApr. 24,1894.

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NIIED STATES PATENT OFFICE.

WILLIAM MOPHERSON, OF NEW YORK, N. Y.

DOVE TAlL|NG-MACH|NE.

SPECIFICATION forming partof Letters Patent No. 518,824, dated April 24,1894.

Applica i n filed December 5,1392. Serial No. 454,078. canine.)

To aZZ whom it may concern:

lie it known that I, WILLIAM MCPHERSON, a c1t1zen of the United States, residing in the city and county of New York, in the State of New York, have invented a certain new and nsefulImprovementin Dovetailing-Machines,

of which the following is a specification.

. The invention makes the blind dove-tail recesses which receive the dove-tail ends of another board. It makes the recesses matchlng exactly to the dove-tails out in the ordinary form on the other piece.

Theimprovedmachine may be made of any s ze, but the invention is intended more particularly for small machines operated by manual power. I will describe it as so operated.

The machine employs a pair of chisels carried 1n properly inclined guides, and having the cutting edges ground at a correspond- 1ng angle. These chisels are brought down simultaneously and cut their corresponding parts not of the same recess but of two adjacent recesses, one chisel cutting the inclined s de of the first, inclining to the right, and the other similarly cutting the inclined side of the second, inclining to the left, numbermg the recesses from right to left. The board to be treated is previously nicely squared and clamped upon the uppermost part of a duplex carriage, and the feeding is elfected by moving these carriages. There are two motions, one a slight motion of both carriages, stepby-step, forward,-this determines how thick a shaving shall be taken by the chisels at each descent. The gradual moving of the board forward toward the operator by such feed goes onuntil the out which began on the extreme end of. the board has extended the recessesinward to-the required depth. I provlde mechanism for stopping the operation at the right point, and returning the carriage, causing it to retreat until its end is again a l ttle within the line of the chisels. The motrons so far as yet described have been performed by both the upper and lower carriages. At this juncture I move another, a third chisel, which is guided in horizontal ways, and by its aid smooth the bottom of the recess which is likely to be left a little ridged by the successive cuts. Next, the board with the up er carriage alone is moved to the right vto an extent'just equal to the distance between one recess and the next, and now the treadle being again operated another succesmake them come out even with all widths of The accompanying drawings form a part of this specification and represent what I consider the best means of carrying out the invention.

Figure 1 is a front view of the principal ,part of the machine with the extreme front removed. A section of the horizontal chisel at the front appears near the center of this figure. A piece of wood is shown in place in the act of being treated. Fig. 2 is a corresponding side elevation. Fig. 3 is a side elevation of the extreme front portion showing the adjacent parts in vertical section. Fig. 4 is a corresponding plan view and horizontal section.

Similar letters of reference indicate corresponding parts in all the figures where they appear.

A is a fixed framework of cast iron or other suitable material. Horizontal ways, A, A, A A shown in dotted lines in Fig.1, sup port and guide a carriage B which is capable only of moving right and left. A rack B in its under face is engaged by a pinion O on the feed-shaft O, which is mounted in fixed bearings, and is turned by small increments, as will presently appear. 7

A A are inclined uprights fixed at adjusted distances apart, in which sliding blocks D, D, are guided, carrying chisels D, D

These chisels are not only beveled like ordinary chisels, as shown in Fig. 2, but also have their edges each sufficiently out of the right angle with the line of the length to compensate for the obliquity of their position so that their cutting edges are always level, as shown in dotted lines in Fig. 1. The arrangement is such that each chisel in its descent makes an inclined cut, adapted to produce one side of a dove-tail cavity 4%, and the other chisel,

ICO

correspondingly inclined in the opposite direction, in its simultaneous descent cuts the opposlte side not of the same but of another slm lar dove-tail recess. I will designate each entire dove-tail cavity by the letter on, and the two {parts of which it is constituted, and which are excavated at different times, by adding super-numerals, as m, m

The movements of both the blocks D, D, and their respective chisels are effected at a slngle depression of a trea'dle, not represented, which is connected by rods E to pins set in the blocks D. Slots a are provided in the inclined guides A, A which allow the pins to play, as will be readily understood.

Bf is the upper carriage, mounted on the main carriage B, and capable of a motion transversely to the motion thereof. It is equlpped with clamps B which are adjustable on the carriage B and equipped with clamping screws B adapted to serve in the obvious manner, clamping the board M which is to be treated.

The feeding of the carriages forward is effected at each ascent of the chisels and their attachments by means of a lever G turning on a fixed center set on an arm on the upright A". ()ne end carries an adjusting screw G which is struck at each ascent of the chisels by a collar D set on the corresponding block D so as to turn the lever G a little, and the motion thus imparted is communicated through a rod H to a lever I turning loosely on the over-hung end of the shaft 0. The other end of this lever carries a pawl .I actuated by a spring J which urges it into engagement with the teeth of a ratchet-wheel G which is keyed or otherwise firmly set on the shaft 0. At each descent of the chisels the lever I is turned by a spring, G in the direc tion to slip the pawl over one or more teeth of the ratchet; and at each ascent of the chisels the lever G is rocked by its receiving a slight blow through the screw G which depresses the rod H and turns the lever I, pulling the pawl J again into its highest position and correspondingly turning the shaft 0 and through the pinion C feeding the carriages B, B with the board M forward. This work proceeds at each descent of the treadle until the board M has been carried forward so far that the dove-tail recesses m, m have been excavated to the required depths by the successive strokes of the chisels D, D

It will be observed that the recesses m excavated by the chisel D is not a part of the same dove-tail cavity to which the recess m excavated by the chisel D belongs. It is one dove-tail space in advance. The chisel D cuts an independent channel in the wood, ready when the other chisel D acts to form its part of a proper dove-tail recess. The width of the chisels should be such that the action of the two completes or nearly completes the proper dove-tail recess. The presence of a very slight ridge at the bottom is of no consequence, but such ridge should be something smaller than is shown in the draw ings.

The bottom of the dove-tail recess is finished smoothly by a separate chisel P of the proper width and having the sides beveled which is mounted in horizontal ways A", and is operated by a lever Q which may be actuated by the hand of the attendant to finish the bottom of each recess m. It traverses at such a level as to remove the roughness left by the descent of the successive chisels, and also the slight ridge, if any, which has been left in the mid-width between the two series of cuts.

When the operator has by the successive descents of the chisels D, D cut the wood for parts of two dove-tail recesses to the exactly proper depth, the feeding is automatically arrested and the carriages B, B, with the wood Mare promptly returned by the force of a weight or spring, IT. Mechanism for efifecting the stoppage of the forward feeding movement and liberating the carriages to allow them to move backward, is shown in Fig. 2.

The ratchet-wheel C has a breadth much in excess of the breadth of the hook-pawl J, and receives also another hook-pawl K, which latter instead of being like the pawl J hung on a movable center is hung on a fixed center, a pin set in the fixed framing A. It is actuated by a spring K, urging it equally with its associate pawl into engagement with the ratchet-wheel 0 Its function is simply to hold the wheel 0 after it has been partially turned by each movement of the pawl K. Each pawl .I and K has a rounded head J K adapted to receive the action of the hammer L and be moved in opposition to the force of their respective springs J, K when the period arrives for liberating the carriages and allowing thereturn motion.

The hammer L turns on a fixed pivot A, and is subject to the force of a volute spring L, tending to throw to the left the head L, which head is of suliicient width to strike the heads J 2 and K of both the pawls. Below the axis of the hammer extends a V-shaped arm L presented, as shown, to a V-shaped ridge 0 on the spring 0. On the side of the carriage B adjacent to the hammer are two adjustable stops B and B. As the carriage moves backward after the chisels have performed their duties and excavated each its respective recess m, m the stop B strikes the head L of the hammer and moves it into the position shown. W'hen the movement of the carriage B and its attachments forward and the excavation of the recesses m, m have proceeded to the proper extent, the stop B pushes the head L of the hammer so far forward that the angle of the arm L passes the angle of the ridge 0. When this condition is attained the hammer moves smartly forward with the force due to the direct tension of the volute spring L and also to the wedgelike action of the ridge 0'. The hammer moves forward and strikes the heads J 2 and K of the respective pawlsJ and K with sufficient force to disengage their hook ends from the teeth of the wheel and hold them out of engagement. Both pawls are thus held out of engagement while the carriage B and its load runs back, when the stop B again performs its work of turning the hammer back to the position shown, and the pawls J and K actuated by their respective springs J and K again engage with the ratchet-wheel C and the work is ready after it has been shifted laterally to be again slowly fed forward in the production of the next dove-tail recess.

The shifting of the board laterally to gage the distance between each dove-tail and the next is effected by sliding the upper carriage B laterally, guided by the tongues B The movement is effected by a bar R carrying a pawl S which engages with a series of teeth B on the front edge of the carriage B The pawl is urged into engagement by a spring S. The bar is moved at the required periods by a handle R. Its motion is limited by stops R R After each backward movement of the carriages with the wood M is completed and the horizontal chisel P has done its work, the attendant moves the bar R to the right as far as it will go, thereby effecting a corresponding movement of the carriage B and the wood M to just the proper extent for the next operation.

I provide for varying the width of the spaces between the several dove-tail recesses when completed. The inclined uprights A A are rigidly held in position during the working of the machine as if they were parts of the fixed framework, but they are capable of adjustment toward and from each other. Each is capable of sliding on its support on the fixed framing A, and carries a nut which is right or left respectively, and receives an endless right and left screw T which is mounted in fixed bearings in the framing A, and may be turned by a wrench applied to the squared end in the obvious manner. F are holding-down bolts which extend up through slots, and F are nuts fitted thereon by turn ing down which the uprights are held very stiffiy after they have been adjusted in position by the screws. Adjusting the slides apart makes the dove-tail recesses m m nearer together, and correspondingly reduces the width of the wood left between the several recesses when completed. To make such adjustment the nuts on the holding bolts F are relaxed, the screw T turned in the proper direction, causing the uprights to move apart to the required extent, then the nuts F being again tightly set the uprights are again stiffly held in their new positions.

My machine gives a uniform inclination to the sides of the cavities corresponding to the inclination of the guide-ways in the uprights. The width of the chisels D, D may be varied, and their position may be varied within limits by obvious means so as to somewhat vary the width of the dove-tail recess. The

distance of the dove-tail recesses apart may be varied with great nicety by the well known expedient of providing a number of pawls of different lengths engaging in the teeth at different stages of the movement so as to give the effect of finer teeth, and allow any degree of fineness in the variation of the extent of traverse. Such pawls may all be mounted on the same pin and worked by one movement of the handle. I believe that one, as shown, will suffice for all ordinary uses.

Various other, changes may be made without departing from the principle or sacrificing the advantages of the invention. I can vary the arrangement of the springs for actu ating the hammer L. The spring L may be dispensed with and the spring 0 with its V- shaped ridge 0 depended upon to give a sufficiently smart forward movement to the hammer at the period when it is required to be effective.

I attach importance to the fact that my chisels are arranged to out each a part of a separate and distinct recess,because it allows the two chisels to be brought into action simultaneously, each in its respective recess,

thus eifecting a great saving of time over what would be required if one chisel had to descend and return before the other could descend.

I attach importance to the provisions for automatically liberating the carriage and al-. lowing it to return after each cut, by accu mulating power in the spring 0, before the feeding is concluded, and using it through the intervention of the hammer L to forcibly and reliably move the pawls J K into their idle positions; and to the fact that in theres turning movement the step B by the act of turning the pawls J K into the position for engagement, returns the hammerL again into its oppositely inclined position, and all the parts are again reliably set for'effective feeding. This mechanism avoids all chance of leaving the parts in an intermediate position.

I claim as my invention 1. In a dove-tailing machine, two inclined chisels carried in inclined ways, set at such distance apart that they will each cut respectively parts of two separate and distinct dove-tail recesses, in combination with mechanism adapted for bringing down both chisels simultaneously and with mechanism to feed the wood forward a proper amount at each cut and with mechanism to change the position of the table carrying the wood after each recess is completed, substantially as herein specified.

2. In a dove-tailing machine, two inclined chisels carried in inclined ways, adapted to out respectively parts of two dove-tail respecified for automatically liberating and ala single operation a small quantity from the lowirng, the carriage to be returned after each bottom of each dove-tail recess, all arranged movement, substantially as herein specified. for joint operation substantially as herein I5 3. In a dove-tailing machine, tWo inclined specified.

5 chiselscarriedininclined ways, set ata proper In testimony that I claim the invention distance apart to cut respectively parts of above set forthI aflix my signature in prestwo separate dove-tail recesses, and mechan- I once of two Witnesses. ism adapted to feed the Wood forvvard a WILLIAM MOPHERSON proper amount at each cut, in combination 10 with the horizontal chisel and the lever Q adapted to be operated after the dove-tail recess is otherwise completed, and to remove at lVitnesses:

M. F. BOYLE, CHARLES R. SEARLE. 

